J. K. Doylend

Two-dimensional free-space beam steering with an optical phased array on silicon-on-insulator

We demonstrate a 16-channel, independently tuned waveguide surface grating optical phased array in silicon for two dimensional beam steering with a total field of view of 20° x 14°, beam width of 0.6° x 1.6°, and full-window background peak suppression of 10 dB.

Silicon on ultra-low-loss waveguide photonic integration platform.

We demonstrate a novel integrated silicon and ultra-low-loss Si3N4 waveguide platform. Coupling between layers is achieved with (0.4 ± 0.2) dB of loss per transition and a 20 nm 3-dB bandwidth for one tapered coupler design and with (0.8 ± 0.2) dB of loss per transition and a 100 nm 3-dB bandwidth for another. The minimum propagation loss measured in the ultra-low-loss waveguides is 1.2 dB/m in the 1590 nm wavelength regime.

Widely tunable Vernier ring laser on hybrid silicon

A hybrid silicon tunable Vernier ring laser is designed and fabricated by integration of two intra-cavity ring resonators, hybrid III-V-on-silicon gain elements, and resistive heaters for thermal tuning. Thermal tuning of more than 40 nm is demonstrated with side mode suppression ratio greater than 35 dB and linewidth of 338 kHz.

Fully integrated hybrid silicon two dimensional beam scanner

In this work we present the first fully-integrated free-space beam-steering chip using the hybrid silicon platform. The photonic integrated circuit (PIC) consists of 164 optical components including lasers, amplifiers, photodiodes, phase tuners, grating couplers, splitters, and a photonic crystal lens. The PIC exhibited steering over 23° x 3.6° with beam widths of 1° x 0.6°.

Fully integrated hybrid silicon free-space beam steering source with 32 channel phased array

Free-space beam steering using optical phased arrays is a promising method for implementing free-space communication links and Light Detection and Ranging (LIDAR) without the sensitivity to inertial forces and long latencies which characterize moving parts. Implementing this approach on a silicon-based photonic integrated circuit adds the additional advantage of working with highly developed CMOS processing techniques. In this work we discuss our progress in the development of a fully integrated 32 channel PIC with a widely tunable diode laser, a waveguide phased array, an array of fast phase modulators, an array of hybrid III-V/silicon amplifiers, surface gratings, and a graded index lens (GRIN) feeding an array of photodiodes for feedback control. The PIC has been designed to provide beam steering across a 15°x5° field of view with 0.6°x0.6° beam width and background peaks suppressed 15 dB relative to the main lobe within the field of view for arbitrarily chosen beam directions. Fabrication follows the hybrid silicon process developed at UCSB with modifications to incorporate silicon diodes and a GRIN lens.

InP photonic integrated circuit for 2D optical beam steering

InP photonic integrated circuit for 2D (5°×10°) optical beam steering has been demonstrated for the first time. Design, fabrication, and preliminary results are presented.

Free-space beam steering in two dimensions using a silicon optical phased array

We report an independently tuned 16-channel optical phased array fabricated in silicon for 2D free-space beam steering. The phased array was composed of silicon-on-insulator waveguide surface gratings integrated with thermo-optic phase tuners and was operated both using a control algorithm together with automated real-time far field image analysis to target and shape the beam, and using a lookup table without real-time feedback. The device exhibited 1.6° × 0.6° beam width and 10 dB background suppression in the far field across a 20° × 14° field of view. We show that by increasing the waveguide width from 1 μm to 3 μm we can suppress the side-lobe peaks by a factor of 2.

Demonstration of a wavelength monitor comprised of racetrack-ring resonators with defect mediated photodiodes operating in the C-band

A CMOS compatible wavelength monitor comprised of two thermally tuned racetrack-ring resonators with defect mediated photodiode structures is experimentally demonstrated in monolithic silicon. Each resonator is independently tuned so as to determine an unknown input wavelength by tuning the resonance peak locations until there is overlap between the two comb spectra. The presence of two of these resonator/heater components, each with a different free spectral range, increases the unambiguous measurement range when compared to one component used on its own.

Hybrid silicon free-space source with integrated beam steering

Free-space beam steering using optical phase arrays are desirable as a means of implementing Light Detection and Ranging (LIDAR) and free-space communication links without the need for moving parts, thus alleviating vulnerabilities due to vibrations and inertial forces. Implementing such an approach in silicon photonic integrated circuits is particularly desirable in order to take advantage of established CMOS processing techniques while reducing both device size and packaging complexity. In this work we demonstrate a free-space diode laser together with beam steering implemented on-chip in a silicon photonic circuit. A waveguide phased array, surface gratings, a hybrid III-V/silicon laser and an array of hybrid III/V silicon amplifiers were fabricated on-chip in order to achieve a fully integrated steerable free-space optical source with no external optical inputs, thus eliminating the need for fiber coupling altogether. The chip was fabricated using a modified version of the hybrid silicon process developed at UCSB, with modifications in order to incorporate diodes within the waveguide layer as well as within the III-V gain layer. Beam steering across a 12° field of view with ±0.3° accuracy and 1.8°x0.6° beam width was achieved, with background peaks suppressed 7 dB relative to the main lobe within the field of view for arbitrarily chosen beam directions.

Free-space beam steering using silicon waveguide surface gratings

An optical phased array for free-space beam control is proposed, designed, and fabricated by integration of surface gratings and phase tuners within a waveguide array. Two methods of characterizing the beam are demonstrated to measure the wavelength-dependent emission versus duty cycle and width.